Commercial products based upon compositions containing thioglycolates, sulfites or alkali metal hydroxides, such as sodium hydroxides, have been widely used to permanently straighten unstraight hair, especially to straighten unstraight Negro hair. Of these products, the thioglycolate compositions and the sulfite compositions which have been commercially marketed have been relatively ineffective, with the hair in many cases reverting at least partially to the original unstraight form. While very effective in producing the desired straightening effect, sodium hydroxide compositions are very harsh to both the scalp and the hair, and the use of such compositions has resulted in numerous instances of scalp irritation and/or burning, and has also resulted in a substantial reduction of the strength of the treated hair, and even, in some instances, considerable hair loss.
Various guanidine compounds have been evaluated by the prior art in hair waving or hair straightening compositions. Of these guanidine thioglycolate appears to have had the most attention by researchers in this art. See, for example, Shansky, American Perfumer and Cosmetics, Volume 78, August, 1963, 32-34; Bogaty et al, American Perfumer and Cosmetics, Volume 78, November, 1963, pages 45-47; and Shansky, American Perfumer and Cosmetics, Volume 78, December, 1963, pages 29-30.
Various organic bases including guanidine have been found to accelerate the dehairing effect of calcium hydroxide suspensions. See, e.g. Barry, "Delipatories" Cosmetic Science and Technology, Edited by Balsam and Sagarin, 2nd Edition, Volume 2, Chapter 18, page 39, 45, Wiley Interscience, New York, 1972 and Barry "Depilatories" Cosmetic Science and Technology, Edited by Sagarin, First Edition, Chapter 20, page 461-462, Interscience Publishers, New York, 1957, and references cited therein.
U.S. Pat. No. 3,157,578, Nov. 17, 1964, discloses compositions for the permanent waving of human hair utilizing a solution containing, e.g., thioglycollic acid and guanidine carbonate. These compositions are employed in the form of aqueous solutions having a pH value of from 7-9, with the guanidine used to replace ammonia used previously thereto, both to function as a neutralizing agent for the acid reducing agent, and also in the form of ammonium carbonate for pH control.
U.S. Pat. No. 3,861,868 of Jan. 21, 1975 acknowledges, in column 1 thereof, earlier abandoned applications relating to the use of guanidine salts in hair drying compositions and hair bleaching compositions.
British Pat. No. 1,274,565 of May 17, 1972 discloses a process for the straightening of human hair wherein the hair straightening is conducted in two separate stages. In the first stage, a known keratin softening substance, such as an alkali hydroxide, sulfite or bisulfite, or a salt of a mercaptocarboxylic acid, is permitted to act upon the hair. After the extensive removal of the keratin softening component, a media containing a swelling substance is applied to the hair. Suitable swelling agents include monovalent aliphatic alcohols, aromatic alcohols, aliphatic diols, ether alcohols, sulfoxides, sulfones, thiocyanates, thiourea and urea, and water-soluble derivatives thereof.
U.S. Pat. No. 3,865,930 of Feb. 11, 1975 discloses a permanent wave composition based on a two-stage operation, wherein in the first stage the S--S linkages of the keratin fiber are opened at an alkaline pH with the addition of a reducing agent such as a thiol. The hair is then treated in a second stage with an oxidizing or neutralizing agent to reconstitute the S--S bridges, so as to impart to the hair the desired configuration. The patent relates to a composition for the aforesaid second stage, wherein the S--S bridges are reformed. This composition is a two-component composition, with one component based on a water-soluble sulfite, bisulfite, metabisulfite, or thiourea, and the other component is hydrogen peroxide.
U.S. Pat. Nos. 2,817,342 of Dec. 24, 1957 and 2,840,086 of June 24, 1958 relate to permanent waving compositions based upon sulfite-type materials. Among other acid sulfites disclosed are an acid solution of guanidine bisulfite, formed by bubbling sulfur dioxide gas into an aqueous solution of guanidine carbonate.
Japanese Pat. No. 76-9013 discloses hair waving or straightening treatments wherein the hair is initially treated with a weak alkali, followed by a treatment with a chelating metallic salt solution. Calcium oxide or calcium hydroxide is used as a chelating agent to prevent mutual interactions of the active ingredients.
U.S. Pat. No. 2,836,543 of May 27, 1954 discloses the use of guanidine as a swelling agent component in a hair setting composition. The composition also includes a water-soluble sulfite and a polyfunctional aromatic additive compound, such as genetistic acid, which acts as an accelerator.
U.S. Pat. No. 3,642,429 of Feb. 15, 1972 is directed to a hair treatment composition based on a polycondensate of methylol compounds and an urein compound. The generic formula for the urein compound appears to encompass guanidine, but guanidine is not named in that patent.
U.S. Pat. No. 3,686,296 is directed to depilatories which are nitrogen-based thioglycerol molecular complexes. The nitrogen base may be, e.g. guanidine or guanidine hydrochloride.
U.S. Pat. No. 3,971,391 of July 27, 1976 is directed to a method of improving the qualities of human hair by converting a part of the cystine links in the hair to lanthioline links. Human hair is treated with certain alkaline and alkali metal hydroxides, and in one embodiment the composition can also include a lanthionization activator. Among various lanthionization activators disclosed is guanidine carbonate (column 4, line 50). The patent is directed to a process for improving hair quality, and not to a hair setting process, with a subsequent setting step being necessary if set hair is desired.
U.S. Pat. No. 2,261,094 of Oct. 28, 1941 is directed to an invention for treating fibrous substances containing keratin, such as wool or hair, wherein a two-step treatment is used. The keratin-containing substances are treated with a reducing agent to affect reduction and disruption of the constituent disulfide or cystine bonds of the keratine, with formation of sulfphydryl groups. Thereafter, the keratin-containing substance, while maintained in the desired form, is treated with a solution of a polyvalent compound, or with an organic compound containing two or more reactive hydrogen atoms, to form sulfur bonds in or between the fiber molecules (note column 1, first column, line 48 through second column, line 6 of the patent). The patentee stresses "it is essential that the treatment with the reducing agent to disrupt the disulfide bonds should proceed as a separate step with the treatment with the polyvalent metal compound or organic compound" (page 1, second column, lines 38 through 42).
U.S. Pat. No. 3,154,470 of Oct. 27, 1964 is directed to a depilatory composition containing four ingredients, namely an emollient base (column 1, lines 41 through 61), water (column 1, lines 62 and 63), a solid basic material (column 1, line 64 through column 2, line 1), and a substitution thiol (column 2, lines 2 through 8). The patent indicates that the substituted thiol is "the essential active depilating agent," note, for instance, column 1, lines 11 and 12, column 2, lines 2 and 3, as well as column 3, lines 66 and 67. The emollient base of the patent serves to provide a protective mantle to prevent skin irritation (note column 2, lines 9 and 10, while the water is emulsified with the emollient base to provide a cream-like consistency to the emollient base (note column 3, lines 61 and 62). The solid basic material, which can be any of guanidine or the alkali and alkaline earth metal hydroxides, carbonates, silicates and tribasic phosphates, functions as "the activating agent for the tioglycolate" (note column 4, lines 15 through 18).
Commonly assigned, copending U.S. application Ser. No. 805,149, filed June 9, 1977 in the name of Mario J. de la Guardia, discloses a composition and process for hair straightening and hair curling. The active hair straightening and curling ingredient of Ser. No. 805,149 is guanidine hydroxide prepared by reacting guanidine carbonate or other suitable guanidine salt with calcium hydroxide or other suitable inorganic hydroxide. Products made in accordance with Ser. No. 805,149 have been on the commercial market in the United States for some while, and have achieved outstanding commercial acceptance. However, because of stability problems, the composition of Ser. No. 805,149 has been marketed as a two-component system, with the guanidine carbonate in one component and the calcium hydroxide in the other component. The guanidine hydroxide in an aqueous guanidine hydroxide solution tends to be converted to guanidine carbonate upon exposure to atmospheric carbon dioxide, so that stability problems arise unless the two components of the system are mixed together and allowed to react, thus forming guanidine hydroxide, only shortly before use. Another disadvantage of Ser. No. 805,149 is that the hair treating composition formed from the two component system commercial product includes calcium carbonate in the composition which is applied to the hair, and the calcium carbonate can lead to complaints of gritty deposits on the hair.